The present invention generally relates to procedures and devices for diagnostic and therapeutic medical procedures requiring use of intravenous catheters, such as those used in cardiac angioplasty. More specifically, the invention relates to guiding catheters such as those suitable for use as a part of catheter systems including those which are used for radiopaque dye injection, for the deployment of laser catheters or other therapeutic devices.
Guiding catheters are used for placing balloon and laser catheters and other medical devices into the desired body vessel, typically a blood vessel such as an artery. Such an artery may be located in or near the heart, brain, abdomen, or peripheral regions. Often, the catheter is inserted into an artery of the arm or leg and threaded to the desired location. The guiding catheter thus becomes the pathway for the other therapeutic or diagnostic medical device.
Since guiding catheters have maneuverability limitations, a guidewire is sometimes inserted first. In these instances, the guiding catheter is inserted over the guidewire. Usually, the guidewire then is withdrawn and the diagnostic or therapeutic catheter introduced through a lumen of the guiding catheter.
Characteristically, the end of the guiding catheter is often formed with a desired curvature to conform to the shape of the location to be treated such as in an artery or to improve maneuverability. The tip is often soft to substantially lessen the risk of trauma to the vessel walls during insertion and/or treatment.
In a typical guiding catheter, the main length, or body, of the guiding catheter is designed for a balance of strength and flexibility. Flexibility improves the ability of the body of the catheter to negotiate the tortuous paths of branching, curving, and narrowing arteries. Those practiced in the art also try to make the body strong by giving it a high torsion modulus and column strength. It has been determined that a strong body reduces the undesirable characteristics called kinking and "whipping" and increases the desirable characteristic called "backup" support.
Catheters sometimes demonstrate "whipping," which is caused by spring torsion. With high spring torsion, the physician experiences a lag in rotational response followed by rotational acceleration. It has been determined that a high torsion modulus reduces the spring torsion and hence the whip. High column strength has been found to improve the ability of the catheter body to withstand lateral forces, axial forces and improve "backup" support. Backup refers to the guiding catheter's ability to provide a reference or backboard for the therapeutic or diagnostic catheter. High column strength also improves the ability of the catheter body to withstanding kinking, and to reduce the angle of kinking when it does occur.
Designs which attempt to balance flexibility with strength generally provide a compromise in performance. Prior approaches designed to improve catheter performance include blending polymers to create desired harnesses (U.S. Pat. No. 4,898,591), multiple layers of polymers (U.S. Pat. No. 4,636,346 and U.S. Pat. No. 4,596,563), and molding polymers over metal braiding (U.S. Pat. No. 4,898,591). Thus, catheters may tend to be designed for maximum rigidity while allowing their minimum acceptable maneuverability. Some prior art has utilized a two segment design which permits better matching of catheter performance for artery location. U.S. Pat. No. 5,342,386 features a more flexible distal segment to improve distal maneuverability in a therapeutic balloon catheter. U.S. Pat. No. 5,171,232 utilizes a braided body and an unbraided transition proximal of the atraumatic tip, giving this therapeutic, diagnostic or guiding catheter greater flexibility in a distal segment.
The present invention is a guiding catheter comprised of several segments which are tailored to meet the maneuverability and firmness needs which vary along the length of a blood vessel. Thus, this invention is firmest at its elongated proximal end portion and most maneuverable at its distal end portion. It is the intent of the invention to have the firm elongated proximal end portion create a firm platform location for the more flexible portion of the catheter at a location which is distally remote and generally coincides with the beginning of a curved or arched area within the vessel. This will provide the greatest controllability at the distal end.
For example, when performing many angioplasty procedures, the guiding catheter is inserted at the leg in the femoral artery about 36 inches (about 90 cm) from the heart artery requiring dilation. Most patients have a substantially straight length of blood vessel, perhaps 29 inches (about 73 cm) in length. This straight length of blood vessel is ideal for a firm catheter body that provides a guiding catheter segment which resembles a "broom handle". In this example, the catheter would then need to maneuver through the aortic arch and perhaps even subsequently smaller vessels with sharper turns. It is not until the aortic arch that the catheter requires considerable flexibility, but the distance from the arch to the coronary arteries is only about 6 to 12 inches (about 15 cm to 30 cm). It is the intent of this invention to design the first or proximalmost segment to be substantially rigid and thus improve the maneuverability of the more flexible distal segments secured thereto.
The firmer catheter segment which extends to an optimum location acts as a relatively long handle that provides more efficient transmission of torque, axial and lateral loads from the hub location to the distal tip location. Thus, with the present invention, the physician experiences improved response when turning the catheter at the tube, when pushing it into the blood vessel and when bending it, all actuated from the hub at the proximal end, as well as when proceeding with diagnostic or treatment catheter backup maneuvers to facilitate passage through a lesion or stenosis.
It is a general object of this invention to provide a catheter more maneuverable and more responsive to the physician's manipulation at the proximal end than are prior guiding catheters.
Another object of this invention is to provide an improved guiding catheter having an in-body platform location therealong in order to provide greater control of more flexible catheter segments distal of this platform location.
Another object of the present invention is to provide an improved guiding catheter having more efficient transmission of torque from the proximal end to the distal end.
Another object of this invention is to provide more efficient transmission of axial loads from the proximal end to the distal end of a guiding catheter.
Another object of this invention is to provide more efficient transmission of lateral loads from the proximal end to the distal end of a guiding catheter.
Another object of the present invention is to provide a firmer guiding catheter surface on which a balloon catheter or the like can be supported when maneuvering it through tight turns or stenoses.
Another object of the present invention is to reduce the likelihood of kinking due to torque, axial or lateral loads applied to a guiding catheter.
Another object of this invention is to reduce the angle of kinking when it does occur during insertion of a guiding catheter.